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A Farewell to Coax And Twisted Pair?

James O’Neal

A BUNKER IN THE SHENANDOAH — I came away from the IBC Show last month with a lot of good information about new broadcast products and the latest technologies. Takeaways include the observation that 4K video is still red hot, while—rather predictably— 3D has withered on the vine (I found only two exhibitors displaying 3D). Another takeaway was a little more subtle, but woven throughout the show nonetheless. This is the growing movement to break away from conventional broadcast infrastructures and move completely into the world of IP. One exhibitor was not so restrained about this, with strategically placed posters declaring it was time to euthanize SDI video and move full tilt to an IP environment.

That was a very strong statement and one that stayed with me throughout the show and beyond. Is it really time for broadcasters to shun the bricks (hardware boxes and modules) and mortar (good old 75 ohm coax and shielded twisted pair audio line) approach for creating infrastructures?

The concept of discrete equipment and “conventional” copper interconnectivity has been around since the birth of broadcasting. The interconnectivity part actually predates broadcasting as it stemmed from the phone company—Ma Bell pioneered both balanced audio lines and coax. Broadcasters jumped on the bandwagon early on (twisted pair audio in the 1920s, and coax when television launched a decade later). Any other sort of connectivity was heresy. Wish I had a penny for every foot of shielded twisted pair and coax that I’ve helped pull and terminate!

Of course I can’t ignore fiber-optic cable as it’s gradually entered the world of broadcasting and is now the choice for hauling signals around in very large plants and sports venues. However, I think many of us tend to view it as a sort of specialized coax once the termination process was streamlined and cheaper interfaces were developed.

Things were quite different when the new kid on the block—“Category-XX” or “CAT” data cables arrived. Even though they’re an offshoot of twisted pair technology, I don’t think many broadcast engineers really gave them much thought early on. They fell within the provenance of the computer geeks, with many of us viewing them as only slightly relevant in broadcasting— certainly not something that would ever displace 600 ohm balanced audio lines, coax, and discrete control cabling.

Fast forward to 2013. After my IBC SDI epiphany, I took note of the exhibitors who have been moving rather steadily during the past few years to connectivities not involving conventional coax and twisted pair, as well as those who now have complete end-to-end IP solutions. At the end of the day it seemed that a very large number had moved or were beginning to move into the IP camp.

Now to someone who has been involved in the broadcasting business for a half a century, this is a bit scary. However, as with so many other changes in our world, it’s something that has to be accepted. Think about how the engineering textbooks have already been turned to a fresh page regarding tube cameras, videotape recorders, CRT displays and analog transmitters.

The same goes for such long-standing “conventional” building blocks used in creating broadcast plants—proc amps, color correctors, standards converters, and the like. More and more of the duties formerly handled by such hardware-based boxes are now being performed by software and high-speed microprocessors.

Twenty-first (and late 20th) century technology has made it possible to do many things that would have been cost-prohibitive, or even impossible, with older technologies. I got word recently about a new television operation constructed with the studio separated from its control room by 150 miles. Everything—production switcher, cameras, intercom, c.g., prompter— in the design was selected to be IPbased and accessible via a web browser. And as long as there’s Internet connectivity, the control room could be anywhere in the world!

Better, cheaper, faster has indeed won out in the broadcast plant. Like it or not, IP is the new king. Yes, it’s going to be a while before we’re going to be moving 3G around on a CAT cable, so there will be a period where “conventional” and new technologies co-exist, but the train has left the station and isn’t going to stop or back up for anyone.

Of course there’s a downside too—troubleshooting a problem is going to be much more difficult in an infrastructure where you can’t swap modules, cable around an obvious problem, or directly probe and check video and audio signals. However, that’s the price we sometimes have to pay for progress.

What to do now with my trusty old coax connector crimp tool and soldering iron?